(1) Field of the Invention
This invention relates to a process for preparing aromatic polysulfones, including polysulfone ionomers and other derivatives, involving the formation of novel metalated polymer intermediates. The polymers so produced exhibit improved or modified properties, which can be tailored to a desired end use by controlling the nature and degree of derivitization. The polysulfones so produced may, for example, be used for forming membranes, fibres, films, sheets and solid structures.
(2) Discussion of the Prior Art
Polysulfones are a very stable class of polymers. However, the molecule generally lacks any usable functionality, rendering polysulfones useful only for applications in which their hydrophobic unreactive state is of advantage, for example in pipes and molded forms, as well as ultrafiltration and reverse osmosis membrane supports.
Hitherto, it appears that only one type of polysulfone has been lithiated. J. M. J. Frechet, M. J. Farrall and C. G. Willson report in Applied Polymer Science Proceedings, 46, pg. 335-9 (1981) that aliphatic poly- (alkene sulfones) were subjected to lithiation. However, considerable chain degradation occurred, with the molecular weight of the product being about seven times lower than that of the starting polymer.
The modification of aromatic polymers by lithiation has been reported, for example, in U.S. Pat. No. 3,402,144 (Allan S. Hay) where polyphenylene ethers were metalated with alkali metal alkyls or aryls to give activated alkali metal-containing polymers. U.S. Pat. No. 3,639,337 (Johann F. Klebe) discloses conversion of poly-(2,6-diphenyl-1,4-phenylene oxide) to a copolymer by metalating the meta position of some of the phenylene rings and reacting the metalated product with carbon dioxide, an aryl aldehyde or a diaryl ketone to produce polymers still retaining the high temperature characteristics of the poly(2,6-diphenyl)-1,4-phenylene oxide) but having the added property of moldability. While the processes taught in these patents are useful, it is not possible to metalate polysulfones by them.